A purpose of a communication system is to rapidly, reliably and sometimes securely transmit information from a source to a destination. The source has many forms, such as voice, data, image and video. In the communication system, there are many types of channels for transmitting information, including a mobile communication channel, a satellite communication channel, an optical fiber communication channel, an underwater acoustic communication channel, an infrared communication channel, a copper cable transmitting channel and a data storage channel. Generally, noises and interferences of different levels are usually brought into the channels, thereby lowering the accuracy of the information. In order to resist the noises and interferences, channel coding technologies may be adopted. In brief, the channel coding is to add redundant information to original information at a sending end according to a certain rule, and at a receiving end by using the redundant information, correct errors brought by the channel noises; therefore, the channel coding is also called correction coding.
Low-density parity-check (Low-density parity-check, LDPC) is a coding and decoding scheme that has the performance close to the Shannon limit and can be implemented.
The LDPC decoding includes three steps, that is, storage, decoding computation and outputting. A first code word is stored and then decoding computation is performed on the first code. The decoding computation of the first code word is ended after a second code word is stored, and the decoding computation of the second code word is then started. The decoding computation time of the first code word is the same as the storage time of the second code word. Assuming it takes 5000 clock cycles to store a code word and takes 500 clock cycles to finish a decoding iteration in the decoding computation, 10 decoding iterations may be completed, and the performance of the decoding computation is closely related to the number of iterations.